632 research outputs found
Generalized Synchronization of Different Chaotic Systems Based on Nonnegative Off-Diagonal Structure
The generalized synchronization problem is studied in this paper for different chaotic systems with the aid of the direct design method. Based on Lyapunov stability theory and matrix theory, some sufficient conditions guaranteeing the stability of a nonlinear system with nonnegative off-diagonal structure are obtained. Then the control scheme is designed from the stable system by the direct design method. Finally, two numerical simulations are provided to verify the effectiveness and feasibility of the proposed method
A Method for Evaluating Traveler Information Systems
Incidents account for nearly 50% of traffic congestion in urban areas. The cost of incident-induced congestion is borne by motorists in terms of delays and higher vehicular costs. They also impose costs on commercial carriers and associated businesses. Mitigating the effect of incidents clearly benefits motorists and commercial users. This study provides a method for evaluating the impacts of dynamic traffic information disseminated through a variety of sources in reducing incident-induced congestion. The method can be used by State Departments of Transportation to decide expansion priorities for traveler information systems, taking into consideration their impacts on commercial and non-commercial users. Using a behavioral model, we simulate the movement of trucks and vehicles in a simple transportation network. The results show the benefits of providing real-time information to travelers in incident-induced congestion situations, and capture the different effects of traveler information according to different user/vehicle behaviors, including commercial carriers.Master of City and Regional Plannin
DESIGN AND SYNTHESIS OF CHIRAL N-HETEROCYCLIC CARBENES WITH APPLICATIONS TO ASYMMETRIC SYNTHESES AND SYNTHESIS OF DIBENZAZEPINONES BY PALLADIUM¨CCATALYZED INTRAMOLECULAR ARYLATION OF O-(2¡¯-BROMOPHENYL)ANILIDE ENOLATES
Chiral N-heterocyclic carbene (NHC) ligands were prepared and examined in three asymmetric syntheses (oxindole synthesis, pyrrolidine synthesis and cyanosilylation of aldehydes). The ligand generated from (4R,5R)-1,3-bis(ortho-cyclohexylphenyl)-4,5-diphenyl-4,5-dihydro-1H-imidazol-3-ium tetrafluoroborate provided the best asymmetric oxindole synthesis: yields of oxindoles up to 99% with enantioselectivities (ee) up to 80% were achieved in 3 h; catalyst loadings as low as 1 mol % could be used; the imidazolinium salt can be made efficiently in only two steps. A mechanism for this asymmetric oxindole synthesis was proposed. The rotation barrier of the N-aryl bond in the oxidative addition products was found crucial for the enantioselectivity.A new approach for the convenient synthesis of dibenzazepinones is reported. The key step is the formation of the seven-membered ring through palladium-catalyzed intramolecular arylation of an anilide enolate. The reactions were completed in 10 min at 100 ¡ãC with moderate to excellent yields. Aminodibenzazepinone, the core structure in secretase inhibitor LY411575, can be prepared in five steps from 2-bromophenylboronic acid and 2-iodoaniline in 60% overall yield. The synthesis reported here compares favorably with presently available approaches to this interesting ring system
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Essays on Aging Americans’ Travel Preferences: Behavioral Survey Analyses
The baby boomer generation began turning sixty-five in 2011. Twenty percent of the U.S. population will be over age sixty-five by 2030. Such a rapidly aging population has posed significant challenges to transportation planning and operating agencies since this large number of aging boomers demand dependable transportation access so they can remain independent and age in place. It is crucial to understand, in a timely manner, aging Americans’ travel mode choices, their preferences and perspectives on transportation supports, and communication channels through which they prefer to receive information on existing and new transportation options. My dissertation presents three essays to explore these important and urgent issues.
Essay One uses the 2009 National Household Travel Survey (NHTS) data to investigate whether the predominant travel preference—favoring private automobiles—hold for different groups of aging Americans. The analyses not only include the commonly used travel mode choice factors, such as socio-demographics, built environment, and transportation attributes; but also include behavioral aspects such as attitudes towards safety, congestion, public transit, and walking environment. Results show no evidence that Americans are giving up driving as they age. Therefore, planning as though baby boomers will give up driving private automobiles as they age is not likely to be successful. Results also imply that although it may not be effective for existing seniors, promoting positive attitudes on certain travel options that were otherwise not preferred by middle-aged boomers (e.g., public transit) could be a useful way to encourage this group of boomers to change their future travel mode choices.
Essay Two discusses the design and implementation of my own survey on senior transportation options. A comprehensive survey questionnaire is constructed to target various user groups of senior transportation services, including seniors, caregivers and their elderly dependents, and younger individuals. All these respondents represent current or future customers of senior transportation services. The survey is then successfully implemented via the Amazon Mechanical Turk (MTurk) crowdsourcing platform. Survey data collected from the MTurk platform represents a fairly diversified population; it can capture respondents from different socio-demographic categories, and it shares a similar distribution pattern with the general population data (e.g., U.S. Census) and the large-scale nationwide transportation survey using random sampling method (e.g., NHTS).
Essay Three analyzes my MTurk survey data and investigates the impact of behavioral factors derived from the Theory of Planned Behavior (TPB) on travel mode choices among different user groups of senior transportation services. Survey respondents’ preferences on types of senior transportation supports, as well as respondents’ preferable channels from which they want to receive information about senior transportation options, are also examined. Results show attitude factors (e.g., convenience, preference, and independence) in general are perceived as more important drivers for seniors’ mode choices than other aspects of TPB (e.g., social norm, feasibility, and cost). This indicates more attention should be drawn to attitude factors, rather than the traditional concerns such as feasibility and cost, when designing and implementing interventions on senior transportation services.
Compared to the extant literature, this dissertation research reveals a more comprehensive set of the factors that affect aging Americans’ travel mode choices. In particular, it highlights the important role of behavioral factors in seniors’ travel model choices. This dissertation research also demonstrates that Amazon MTurk can serve as a valuable crowdsourcing platform for planning related surveys, experiments, and data collections, especially when addressing timely issues such as aging Americans’ travel needs. It generates useful insights for researchers and practitioners to develop effective policy and service interventions to improve senior’s transportation access, and to address transportation challenges along with the rapid population aging process
Extended warfarin treatment versus rivaroxaban treatment for first episode of symptomatic unprovoked pulmonary embolism: A prospective cohort study
Purpose: To compare the benefits and risks of extra 6 months of warfarin therapy with those of rivaroxaban treatment in patients with initial unprovoked pulmonary embolism (PE) episode who completed 3- or 6-month of therapy on heparin/vitamin K antagonist standard regime.Methods: This prospective observational study included 212 patients with follow-up from July 2013 to July 2018. The primary endpoint was symptomatic recurrent venous thromboembolism (VT), composite of non-fatal symptomatic PE or deep vein thrombosis or fatal VT, and major bleeding (non-fatal/fatal) up to 6 months. Secondary endpoints were death not related to PE or major bleeding.Results: During the 6-month therapy period, the primary endpoint was seen in 3 out of 106 patients (2.83 %) in warfarin category, and in rivaroxaban category, for a hazard ratio (HR) of 1.22 [95 % confidence interval (CI) = 0.09 - 11.18; p = 0.813]. With warfarin therapy, 2 patients (1.89 %) had recurrent VT, while 3 patients (2.83 %) had VT with rivaroxaban. Major bleeding was observed in 2 patients (1.89 %) on warfarin, and in one patient (0.94 %) on rivaroxaban. During the entire 18-month period, the primary endpoint was seen in 15 patients (14.15 %) treated with warfarin, and in 18 patients (16.98 %) treated with rivaroxaban (HR 0.84; 95 % CI = 0.47 - 1.84; p = 0.431). Major bleeding was observed in 5 patients (4.72 %) under warfarin (one fatal), relative to 3 patients (2.83 %) under rivaroxaban (R 1.67; 95 % CI = 0.62 - 5.95; p = 0.09).Conclusion: Rivaroxaban showed higher efficacy than warfarin in recurrent VT prevention, with lower risk of major bleeding. However, the extended therapeutic benefit was not maintained post-therapy.
Keywords: Pulmonary embolism, Rivaroxaban, Warfarin, Heparin, Vitamin K, Hazard rati
Guanylate-binding protein 1 participates in cellular antiviral response to dengue virus
BACKGROUND: Dengue virus (DENV), the causative agent of human Dengue hemorrhagic fever, is a mosquito-borne virus found in tropical and sub-tropical regions around the world. Vaccines against DENV are currently unavailable. Guanylate-binding protein 1 (GBP1) is one of the Interferon (IFN) stimulated genes (ISGs) and has been shown important for host immune defense against various pathogens. However, the role of GBP1 during DENV infection remains unclarified. In this study, we evaluated the relevance of GBP1 to DENV infection in in vitro model. FINDINGS: Quantitative RT-PCR (qRT-PCR) and Western blot showed that the expression of mouse Gbp1 was dramatically upregulated in DENV-infected RAW264.7 cells. The intracellular DENV loads were significantly higher in Gbp1 silenced cells compared with controls. The expression levels of selective anti-viral cytokines were decreased in Gbp1 siRNA treated cells, while the transcription factor activity of NF-κB was impaired upon GBP1 silencing during infection. CONCLUSIONS: Our data suggested that GBP1 plays an antiviral role during DENV infection
IS BRAIN-DERIVED NEUROTROPHIC FACTOR (BDNF) VAL66MET POLYMORPHISM ASSOCIATED WITH OBSESSIVE-COMPULSIVE DISORDER? A META-ANALYSIS
Background: Brain-derived neurotrophic factor (BDNF) polymorphism plays an important role in neural survival and was proposed to be related to obsessive-compulsive disorder (OCD). Genetic association studies of the BDNF Val66Met polymorphism (rs6265) in OCD have produced inconsistent results. A meta-analysis of studies was conducted to compare the frequency of the BDNF Val66Met variant between cases with OCD and age-matched controls.
Subjects and methods: Electronic databases were searched for eligible articles in English and ten studies on the association of the BDNF Val66Met polymorphism with OCD were analysed.
Results: A total of ten studies involving 2306 cases with OCD and 4968 healthy controls were included. Findings indicated that the BDNF Val66Met polymorphism was not associated with OCD. But there was a marginally significant effect of the BDNF Val66Met variant on OCD in different ethnicity.
Conclusion: Findings from this meta-analytic investigation of published literature provide little support for the Val66Met variant of BDNF as a predictor of OCD. Future well-powered agnostic genome-wide association studies with more refined phenotype are needed to clarify genetic influences on OCD
Single-crystal silver nanowires: Preparation and Surface-enhanced Raman Scattering (SERS) property
Ordered Ag nanowire arrays with high aspect ratio and high density
self-supporting Ag nanowire patterns were successfully prepared using
potentiostatic electrodeposition within the confined nanochannels of a
commercial porous anodic aluminium oxide (AAO) template. X-ray diffraction and
selected area electron diffraction analysis show that the as-synthesized
samples have preferred (220) orientation. Transmission electron microscopy and
scanning electron microscopy investigation reveal that large-area and ordered
Ag nanowire arrays with smooth surface and uniform diameter were synthesized.
Surface-enhanced Raman Scattering (SERS) spectra show that the Ag nanowire
arrays as substrates have high SERS activity.Comment: 5 pages, 4 figure
Multi-view 3D Face Reconstruction Based on Flame
At present, face 3D reconstruction has broad application prospects in various
fields, but the research on it is still in the development stage. In this
paper, we hope to achieve better face 3D reconstruction quality by combining
multi-view training framework with face parametric model Flame, propose a
multi-view training and testing model MFNet (Multi-view Flame Network). We
build a self-supervised training framework and implement constraints such as
multi-view optical flow loss function and face landmark loss, and finally
obtain a complete MFNet. We propose innovative implementations of multi-view
optical flow loss and the covisible mask. We test our model on AFLW and
facescape datasets and also take pictures of our faces to reconstruct 3D faces
while simulating actual scenarios as much as possible, which achieves good
results. Our work mainly addresses the problem of combining parametric models
of faces with multi-view face 3D reconstruction and explores the implementation
of a Flame based multi-view training and testing framework for contributing to
the field of face 3D reconstruction
Mitigation of Unmodeled Error to Improve the Accuracy of Multi-GNSS PPP for Crustal Deformation Monitoring
High-rate multi-constellation global navigation satellite system (GNSS) precise point positioning (PPP) has been recognized as an efficient and reliable technique for large earthquake monitoring. However, the displacements derived from PPP are often overwhelmed by the centimeter-level noise, therefore they are usually unable to detect slight deformations which could provide new findings for geophysics. In this paper, Global Positioning System (GPS), GLObalnaya NAvigatsionnaya Sputnikovaya Sistema (GLONASS), and BeiDou navigation satellite system (BDS) data collected during the 2017 Mw 6.5 Jiuzhaigou earthquake were used to further exploit the capability of BDS-only and multi-GNSS PPP in deformation monitoring by applying sidereal filtering (SF) in the observation domain. The equation that unifies the residuals for the uncombined and undifferenced (UCUD) PPP solution on different frequencies was derived, which could greatly reduce the complexity of data processing. An unanticipated long-term periodic error term of up to ± 3 cm was found in the phase residuals associated with BDS satellites in geostationary Earth orbit (GEO), which is not due to multipath originated from the ground but is in fact satellite dependent. The period of this error is mainly longer than 2000 s and cannot be alleviated by using multi-GNSS. Compared with solutions without sidereal filtering, the application of the SF approach dramatically improves the positioning precision with respect to the weekly averaged positioning solution, by 75.2%, 42.8%, and 56.7% to 2.00, 2.23, and 5.58 cm in the case of BDS-only PPP in the east, north, and up components, respectively, and 71.2%, 27.7%, and 37.9% to 1.25, 0.81, and 3.79 cm in the case of GPS/GLONASS/BDS combined PPP, respectively. The GPS/GLONASS/BDS combined solutions augmented by the SF successfully suppress the GNSS noise, which contributes to the detection of the true seismic signal and is beneficial to the pre- and post-seismic signal analysis
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